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I still have on order w/out paddles as I didnt join this site until after the fact and the dealer told me not needed as most peopel wont use paddles anyway. Since, I've heard many of you rave about using the paddles w/sport trans but I think thats been primarily via the 535. The 550i (not x either) test vehicle didnt have the paddles but I was blown away by the stock acceleration. So, thats why I ask?

I still have on order w/out paddles as I didnt join this site until after the fact and the dealer told me not needed as most peopel wont use paddles anyway. Since, I've heard many of you rave about using the paddles w/sport trans but I think thats been primarily via the 535. The 550i (not x either) test vehicle didnt have the paddles but I was blown away by the stock acceleration. So, thats why I ask?

The sport transmission not only has paddle shifters it also shifts faster and will be faster in drive even if you don't shift manually. At least that's what I read about it. I drove the rear drive 550i with the sport transmission and the shifts were extremely fast. The non sport transmission in Car and Driver this month had 0-60 of 4.8 seconds which is what you experienced. I would guess the sport transmission would be 4.7s, but that's just a guess. I'm getting the sport transmission on my 550i xDrive due in the dealer next week. I actually changed my order several weeks after I put it in to get the paddles. The paddles allow you to upshift and downshift without taking your hands off the steering wheel, a major advantage when driving hard. I would spend the extra $500 for it if it's not too late to add it to your order. I think you won't be sorry.

The sport transmission not only has paddle shifters it also shifts faster and will be faster in drive even if you don't shift manually. At least that's what I read about it. I drove the rear drive 550i with the sport transmission and the shifts were extremely fast. The non sport transmission in Car and Driver this month had 0-60 of 4.8 seconds which is what you experienced. I would guess the sport transmission would by 4.7s, but that's just a guess. I'm getting the sport transmission on my 550i xDrive due in the dealer next week. I actually changed my order several weeks after I put it in to get the paddles. The paddles allow you to upshift and downshift without taking your hands off the steering wheel, a major advantage when driving hard. I would spend the extra $500 for it if it's not too late to add it to your order. I think you won't be sorry.

"Acceleration is determined by the fundamental laws of physics including.

Force = mass times acceleration
Work = Force times distance
Power = Work per unit time
Torque = force times radius

Low speed acceleration is mostly determined by engine torque and torque multiplication by the gears and the final drive. At higher speeds the torque multiplication is less and the negative forces acting on the car are greater, ie wind resistence is greater because the air molecules have to be accelerated to a greater velocity and the kinetic energy imparted to those molecules is dependent on the square of the velocity. This is called drag. In addition, at higher speeds all the frictional forces opposing acceleration are increased. So, at high speeds maximal hp becomes the determining factor in acceleration.

In general an 8 speed transmission will be faster 0-60 than a six speed because the torque multiplication is greater in 1st and 2nd gears. This will be somewhat counterbalanced by a lower final drive ratio but even factoring in this the total torque multiplication in 1st and 2nd gear will still be larger with an 8 speed.

In BMWs the maximum speed in second gear is usually around 62-68 mph. Therefore in a 0-60 sprint there will be only one gear change. In the 8 speed sport automatic tranmission this shift is faster than either the 6 speed or the standard 8 speed auto. Since we know from multiple tests including the current C&D test of the 550i and prior tests of the E60 M5 with manual and SMG that the stick shift is slower, we can surmise that manual shifting prolongs the 0-60 times in high powered V-8 BMWs.

In addition, in high torque vehicles 0-60 is faster in cars with AWD because more of the useful torque can be applied to the pavement without wheel slippage. This is comfirmed by the already published tests comparing the 0-60 times in the 750i vs the 750i xDrive and the Porsche Panmera AWD vs the rear drive version in which the AWD versions with the same engine were faster 0-60 than the RWD versions despite the additional weight of the AWD versions. In other words, the maximum amount of torque that can actually be utilized to accelerate the car is limited by the coefficient of friction between the tires and the pavement and the size of those tires. Four tires can simply transmit more torque than two tires can. At higher speeds the torque multiplication is less and all the torque can easily be tranmitted by just the two rear tires without slippage. So, at higher speeds, the RWD drive cars will accelerate faster than the AWD cars because the RWD cars weigh less."

I can answer any questions you may have about this as well. [At the risk of suffering critcisms of my personality for "arrogance" and "conceit" I will tell you that I was a physicist before I went to med school and obtained my state certification as a high school physics teacher after I retired from medicine.] If my above analysis has any mistakes it's because I may be a little "rusty" and will stand corrected.

Not bad, Rich.
From the standstill to 30 is the biggest advantage of AWD, it diminishes by 60, at which point RWD starts to pull ahead. From the rolling start, RWD will have an advantage.

Thanks. The tests show that the advantage to 30 mph is not overcome by the RWD cars during the 30-60 mph acceleration. That's why the 0-60 times are faster. I don't have any actual data on 30-60 times for these cars. Do you? I wouldn't be surprised if the 30-60 times were very close to the same. I'll check the 5-60 times if I find one. Can you give me a reference?

OK, I found C&D road test of e60 i and xi, but one has manual, another auto (xi)
The numbers are close, xi 0-60 = 5.4, 0-100 = 13.4, rolling start 5-60 = 6
i 0-60 = 5.2, 0-100 = 13, rolling start 5-60 = 6.2
The rolling start is expecially deceiving since xi is auto. They do say, however "It's heavier and a little slower than the rear-drive 535i"

The difference could be auto vs manual. But this comparo is one in which the 0-60 time for the AWD is slower than for the RWD. We are talking about cars like the 750i and the Porsche Panamera in which the 0-60 time is documented to be faster than the same car with AWD. In addition the C&D test indicated the F10 auto was faster 0-60 than the manual in the rear drive car. The test you refer to here the xi was auto and slower than the RWD with manual.

What I was referring to was the same car in AWD vs RWD in which the AWD version is documented to be faster 0-60 and then compare the 5-60 mph times.

TBut this comparo is one in which the 0-60 time for the AWD is slower than for the RWD.

Today's AWD systems are much more efficient than in the past, from a 'physics' point of view overcoming the rotational inertia of older systems had a much greater impact than in newer cars. It's one of the reasons that the S6 never put up expected numbers and performance wise was always a bit disappointing.

I know. I think the best chance is to look for 335i vs x, since those are being tested more often, although they are not heavy enough for our purpose.

Last spring I did read a direct comparo between the 750i and 750i xDrive, I can't remember where I read it but it might have been in Roundel. The AWD was 0.2s faster to 60mph. I don't recall if they did 5-60 mph.

0-60 time determine by how much initial traction you got, so makes sense for xi to have better time here.
And also make sense for xi to loose the top speed to RWD cause more friction introduces by the xfer case (RWD has none). That's pretty much the forum members of e90post have been proving at the drag strip with mod N54s, 0-60, 1/4 mile, top speed etc.

the rwd with sport and the 8 speed zp transmission is faster.....bmw's x drive is not that great...my cousin has a 750 x drive and i dont find it as fun to drive or as fast as my rwd 550 with paddles and the 8speed box